This is a data set derived from a contract which terminated four years ago, entitled "Ethnic Differences" with Columbia University, New York and Northwestern University, Chicago. The project was aimed at addressing the determinants for the well known differences in rates of low birth weight among women of different ethnic groups. Through the departure of several key professional staff members involved in this project (Dr. Shiono, the original project officer, Dr. George Rhoads, a Co-investigator and Dr. Leslie Cooper, who replaced Dr. Shiono as project officer) the analyses of the data have been substantially delayed. The project included about 1100 pregnant women from six different groups (African-American, Chinese, Dominican, Mexican, Puerto Rican, White) who were below 200th percent of the Federal poverty level and were recruited at prenatal care clinics in New York and Chicago. Data were collected through two in depth interviews during the course of pregnancy which included detailed information about social, psychological, medical and lifestyle factors. Women were recruited between December 1987 and December 1989. The study is completed and analysis of data is in progress and one manuscript has been prepared and submitted for publication.